/*
This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or
distribute this software, either in source code form or as a compiled
binary, for any purpose, commercial or non-commercial, and by any
means.

In jurisdictions that recognize copyright laws, the author or authors
of this software dedicate any and all copyright interest in the
software to the public domain. We make this dedication for the benefit
of the public at large and to the detriment of our heirs and
successors. We intend this dedication to be an overt act of
relinquishment in perpetuity of all present and future rights to this
software under copyright law.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to <http://unlicense.org/>
 */
package org.codebistro.util;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Very simple templating system with no external dependencies.
 * Use it when your needs are very simple and you don't have time to implement dependencies and/or
 * learn how the thing works.
 * It is based on Moustache syntax but only have simple variable substitution:
 * <pre>
 *     text...
 *     text{{variable}}more text...
 *     text...
 * </pre>
 * Unlike the rest of the package, this code is in public domain -- just stick it in your project and template away!
 */
public class BristleTemplate {
    String template;

    public BristleTemplate(String template) {
        this.template= template;
    }

    static final Pattern VARIABLE = Pattern.compile("\\{\\{([A-Za-z0-9_]+)\\}\\}");
    
    /**
     * Render my template into `appendable` using variable map in `context`
     */
    public void render(Map<String, Object> context, Appendable appendable) {
        try {
            Matcher matcher = VARIABLE.matcher(template);
            int pos = 0;
            while (true) {
                if (matcher.find(pos)) {
                    appendable.append(template.substring(pos, matcher.start()));
                    String variableName = matcher.group(1);
                    appendable.append(context.get(variableName).toString());
                    pos = matcher.end();
                } else {
                    appendable.append(template.substring(pos));
                    break;
                }
            }
        }
        catch (IOException e) { throw new RuntimeException(e); }
    }

    /**
     * Render my template using variable map in `context` and return rendered value.
     */
    public String render(Map<String, Object> context) {
        StringBuilder result= new StringBuilder();
        render(context, result);
        return result.toString();
    }

    /** Utility function to build a context quickly */
    public static Map<String, Object> context(Object...args) {
        Map<String, Object> result= new HashMap<String, Object>();
        for(int i= 0; i<args.length; i+=2) {
            result.put(String.class.cast(args[i]), args[i+1]);
        }
        return result;
    }


}
